The present invention relates to a venting device (also known as a flatus filter) for attachment to a stoma bag, pouch or the like.
All people periodically expel gases (flatus) through the bowels, but such gas expulsion can cause problems for wearers of stoma bags, pouches or the like, such as colostomy bags, in that the gas tends to inflate the bag and, if there is sufficient build-up of gas within the bag, the bag can become detached from the wearer, with associated discomfort, risk of spillage, and the like. The problem can be overcome simply by periodically partially detaching the bag from the wearer, flattening it by hand to expel the gases, and then reattaching it. That solution can, however, be both tedious and embarrassing, as well as causing risk of leakage of liquid from the bag and possible skin irritation as a result of repeated detachment and attachment of the bag.
In order to overcome those problems, stoma bags have been provided with simple vent openings, which may be merely a small hole, such as a pin-hole, in the bag--and preferably toward the top of the bag to reduce risk of leakage. This is often sufficient to permit the emission of gases from the bag and thus avoid inflation of the bag.
The problem with a simple, continually open, vent, however, is that malodours may also be emitted, causing unpleasantness and embarrassment to the wearer. One way of overcoming that problem is to provide the bag with a controllable valve, which can be opened and closed as desired by the wearer, as described, for example, in U.S. Pat. No. 4,232,672 (which also contains a list of other patent specifications relating to various vented stoma appliances). It may, however, not always be convenient to open the valve in order to release the gases at the times when that proves necessary, and that can also cause embarrassment to the wearer. Moreover, such a valve is relatively complicated and increases the cost of the stoma appliance.
A second way of overcoming the problems associated with a simple, continually open, vent is to combine it with a deodourising means and/or with a filter to absorb the malodours. Various stoma appliances with in-built deodourising means and/or an in-built flatus filter have been described in, for example, U.S. Pat. No. 3,690,320, 3,865,109, GB Nos. 1,379,464 and 1,405,032.
Many commercially available stoma bags do not have such in-built deodourising means or flatus filters, however, and therefore various separate flatus filters are available for attachment to such bags. One such separate flatus filter available for attachment to a stoma bag is similar to an ordinary adhesive plaster but with a charcoal/felt pad in place of the normal absorbent pad of a plaster. It is essentially square, with a plastics backing sheet measuring about 4 cm.times.4 cm and adhesive on one side, and a charcoal/felt pad measuring about 2 cm.times.2 cm centrally situated on the adhesive side of the backing sheet covering a plurality of perforations in the backing sheet. In use, a pin-hole is made in one wall of the stoma bag toward the top and the filter is adhered to the wall of the bag with the charcoal/felt pad over the pin-hole. Gases are emitted from the bag through the pin-hole and then pass through the charcoal/felt pad, for absorption of malodours, before being discharged through the perforations in the backing sheet. A similar flatus filter, but with the charcoal/felt pad enveloped between a gas-permeable sheet, for attachment to the wall of the stoma bag, and a perforated gas-impermeable backing sheet is described in GB No. 1,462,492.
Another type of flatus filter consists of a charcoal/foam annular disc, adhesive on one face and with a circular plastics backing sheet covering the whole of the other face including the central hole. In use, this filter is also placed over a pin-hole in one wall of the bag with the central hole of the disc over the pin-hole. Gases emitted from the bag through the pin-hole, pass into the central hole of the flatus filter and then through the charcoal/foam pad, and out through its circumferential edge.
Yet another type of flatus filter is described in GB No. 1,550,960 and comprises a charcoal/foam or charcoal/felt pad coated on one side with a gas-permeable adhesive layer for attachment over a hole in a wall of a stoma bag, and coated on the other side with a gas-impermeable layer. Again, the gases are discharged through the circumferential edge of the filter.
We have discovered that a disadvantage of all those filters is that it is necessary to make a pin-hole in only one wall of the bag, which entails pulling the two walls of the bag apart and holding them apart while making the hole, which can be awkward. We have also found that sometimes the pin inadvertently pierces the other wall of the bag, or pierces the same wall of the bag in a second position, and this is not noticed, and that gases can then escape without passing through the filter, resulting in unpleasantness and possibly embarrassment to the wearer. Furthermore, the filters are not always adequately effective in absorbing malodours.